A graphene layer is a one-atom-thick planar sheet of carbon atoms that are tightly packed in a two-dimensional honeycomb lattice. Graphene has a high electron mobility at room temperature. Graphene films can be produced in a number of ways, including mechanical and liquid phase exfoliation from graphite, epitaxial growth on crystalline substrate, and reduction from graphene oxides. Chemical vapor deposition (CVD) can be used to produce graphene layers on catalytic metal substrates, and the graphene layers can be transferred to other desired substrates. For example, a graphene layer can be formed on a metal substrate, and transferred from the metal substrate to a destination substrate (e.g., a semiconductor wafer) using a wet-transfer process. The wet-transfer process involves protecting the graphene layer with a supporting polymer layer, etching and removing the metal substrate, transferring the graphene layer to the destination substrate, and removing the polymer layer from the graphene layer.